Vector alignment device



July 28, 1964 H. J. BATES ETAL 3,142,169

vEcToR ALIGNMENT DEVICE Pao/AL July 28, 1964 H. J. BATES ETAL.

VECTOR ALIGNMENT DEVICE s sheets-sheet' 2 Filed July 27, 1962 July 28 1954 H. J. BATES ETAL 3,142,169

VECTOR ALIGNMENT DEVICE Filed July 27, 1962 3 Sheets-Sheet 3 A 2f w n www@ d aras iwf/P74 sy ,wa-'f7.5 Ma/@4V INVENTOR.

BY yf United States Patent 3,142,169 VECTOR ALIGNMENT DEVICE Howard J. Bates, Walnut Creek, Robert A. Spry, R1ch mond, and Robert E. Murray, Oakland, Calif., asslgnors to The Rucker Company, a corporation Filed July 27, 1962, Ser. No. 212,923 6 Claims. (Cl. 73--1) Our invention relates to mechanisms especially useful in automatically arranging a test or environmental support on a centrifuge at a desired angle with respect to both radial and tangential forces.

In recent years there have been made available, primarily for test purposes, centrifuges characterized by the provision of a central base alfording a vertical axis about which a radial arm is revolved. Some centrifuges, usually the smaller ones, at the outboard end of the rotating arm have a specimen table of mount disposed to rotate on another vertical axis parallel to the axis of rotation of the centrifuge. The test or specimen table is rotated about its own axis, through a partial circle, usually by hydraulic means controlled from a remote point. A device of this sort is shown in Patent No. 3,011,333 issued on December 5, 1961 to Roth and Robertson.

More recently, centrifuges of this sort have been made large enough so that an individual person can be subjected to the centrifugal environment, as shown in FIGURE 3. In this instance the individual person is placed within a chamber or capsule. The chamber 6 is spherical and is supported by a gimbal mount 1 at the end of vthe centrifuge arm 2. The gimbal arrangement is such that the capsule or chamber can be rotated by a motor 3 through at least a partial circle about a vertical axis 4 parallel to the axis 5 of rotation of the centrifuge arm 2 on a supporting base 10 containing the driving mechanism, not shown. A centrifuge of this type is shown in the copending application of Drone, Bates and Begg entitled High Energy Centrifuge Drive iiled July 23, 1962 with Serial No. 211,810 and assigned to the assignee hereof.

As the centrifuge arm is brought up to speed from rest, it is usually accelerated under a programmed control and in some instances the acceleration is quite rapid. The rotation of the centrifuge arm can be considered as a motion due to an accelerative force represented by a resultant vector. As usual, this vector can be resolved into component vectors at right angles, one component being tangential and the other being radial. The direction of the radius of the centrifuge arm through its rotational center and the rotational center of the chamber of specimen table is used as the direction of the radial vector. A direction in a horizontal -plane but at right angles to the radial vector and based on the rotational center of the chamber or capsule is used as the direction of the tangential vector. The actual force impressed upon a specimen or felt by an individual person, considered as being located at a point concentric with the vertical axis of the table or chamber, is represented as a resultant vector made up of the vector sum of the stated radial and tangential components.

In many instances it is desired to impose upon the specimen or upon the person being tested a resultant force of a particular value or values. This is especially true during various changes in rotary speed of the centrifuge arm. While it is sometimes desired to test at a constant rotary or angular velocity without change inthe tangential component of the acceleration, it is more often desired to test during changes in the tangential velocity, which constitute tangential accelerations, and it is even further desired to test not only at constant accelerations, but also during changes in acceleration. The change in acceleration is referred to sometimes as onset or more generally ICC The force upon the test table specimen or chamber occupant when the centrifuge is rotating is made up of a component due to gravity, another component acting tangentially and another component acting radially. The gravity component is very small and is disregarded herein. The tangential component Varies with the angular acceleration and with the rate of change of angular acceleration or jerk. The radial component varies with the angular velocity. As the acceleration and jerk of the centrifuge change and as the velocity changes, the direction at which the resultant force is effective upon a specimen or is felt by a test person correspondingly changes. lf the test subject is always to feel the resultant force in the same apparent direction, the angular position of the test table or chamber must be accordingly varied as the operational characteristics of the centrifuge vary.

It is therefore an object of our invention to provide a vector alignment device which can be set to produce any desired resultant force due to centrifuge acceleration'or jerk and correspondingly to position the test table or chamber at the proper angle with respect to its own rotational axis at the end of the centrifuge arm.

Another object of the invention is to provide a vector alignment device in which the Vspecimen table or test chamber is automatically positioned around its vertical axis at an angle relative to or with respect to the radius of the centrifuge arm so as to produce the desired apparent force direction on the specimen or test individual.

A further object of the invention is to provide a vunique centrifuge test environment which isV automatically regulated pursuant to a desired program.

A still further object of the yinvention is in general to provide an improved test device forming part of a centrifuge mechanism.

Other objects together with the foregoing are attained in the embodiments of the invention described in the accompanying description and illustrated in the accompanying drawings, in which:

FIGURE 1 is a simpliiied diagram of a vector valignment device in which a number of mechanical components are utilized.

FIGURE 2 isa simplified diagram of a structure of a comparable nature in which the functions are produced primarily by electronic rather than mechanical components.

FIGURE 3 is a side elevation of a centrifuge with which our vector alignment device is utilized.

With reference rst to FIGURE l, it is considered that a centrifuge of the type described has at the end of the lcentrifuge arm 2a or table 6 chamber mounted'for rotation about the vertical axis 4 parallel to the centrifuge axis 5. Provided in association with the table 6 is a resolver 7 actuated by a connector 8 between the table and the resolver so that the angular table position is transmitted to the resolver 7. The angle is measured in a horizontal plane normal to the rotational axis of the table and is that between a datum radius ofthetable and the centrifuge arm radius. In this way the resolver receives an input indicative of the angular orientation of the table 6 about its rotational axis.

Under many circumstances it is desired .to have a manual setting or control of this angular position of the table. For that reason there is provided at a remote point any sort of well-known control 9 (illustrated diagrammatically) which can be varied to indicate or to set to one or more of the angular positions it is desired the table 6 to assume. When the control 9 is set to a desired value, and when a switch 11 occupies a dotted line position, as shown in FIGURE l, a functional .circuit 12 is established from the control input 9 through a path 13 to the resolver 7. The resolver compares the input from the shaft 8 indicating the actual table position with the input from the path 13 indicating the desired table position and is effective t determine the difference of their values to establish or indicate an errorf The value of this error is impressed upon an output path 14. The energy available is usually a very small amount so is sent through an amplifier 16. From the amplifier the enlarged signal travels on a path 17 to a demodulator 18 so that the signal is made effective through a path 19 upon a servo valve 21. Correspondingly, the valve is effective through a path 22 to control the amount and direction of rotation of a motor 23. Conveniently this is an axial piston fluid motor which is responsive to the input impulse. The motor is functionally joined through a path 24 with suitable reduction gearing 26 connected through a representative path 27 with the table or chamber 6 so that the rotation of the motor 23 produces a corresponding orientation of the table 6. As the table assumes its new position, that position is transferred through the pathway 8 to the resolver 7 and therein is again compared with the input to the resolver through the path 13. As soon as the table position corresponds with the required position, there is no further output from the resolver, the motor 23 stops and the table 6 is positioned exactly in accordance with the input from the regulated source 9.

Pursuant to the invention, there is provided in addition to the remote input 9, which can be manual or can come from some other program device, an arrangement for positioning the table or chamber 6 in accordance with a desired direction of the vectorial resultant of the radial force and the tangential force acting upon the table 6 or chamber at all times during the functioning of the centrifuge.

To carry out this invention, we provide on the centrifuge arm at any convenient location but preferably close to the mounting of the table or chamber 6 a pair of accelerometers 31 and 32. The accelerometer 31 is arranged so as to be responsive to a radial force component on the centrifuge arm, whereas the other accelerometer 32 is responsive to a tangential force component upon the same object. The desired resultant vector is the vectorial sum of the radial vector and the tangential vector as described and its direction is represented by an angle between the radius of ,the centrifuge arm and the resultant force vector. The radial accelerometer 31 when responding to a radial force affords an output on a path 33 that becomes an input to a cosine potentiometer 34 mounted on a rotary shaft 35. Comparably, the output of the tangential accelerometer 32 when responding to a tangential force travels over a path 36 and becomes an input to a sine potentiometer 37 also mounted on the common shaft 35.

The potentiometers 34 and 37 have characteristic windings. The angular position of the shaft 35 produces an output from the cosine potentiometer 34 in a path 38 so that the value of the output is proportional to the cosine of the angle of the position of the shaft 35. The cosine input is considered as a negative value. The potentiometer 37 is so wound as to provide an output in a path 39 comparable to sine of the angle of the shaft 35. Both the resulting cosine and sine values are impressed upon a servo amplifier 41 to increase them proportionally and the resultant value, the algebraic sum of the sine of the shaft angle and the cosine of the shaft angle, is transmitted over a path 42. The signal in the path 42 is impressed upon a servo motor 43 connected to the shaft 35 by a proportional gearing 44. When the servo motor 43 is rotated, the shaft 35 is correspondingly rotated through the gearing 44 until the shaft 35 is brought to an angular position such that both the cosine potentiometer 34 and the sine potentiometer 37 produce values of output which when taken together through the servo amplifier 41 produce no further rotation of the servo motor 43. Thus the shaft 35 is positioned in accordance with inputs from the accelerometers 31 and 32.

An input resultant which will produce no further rota tion of the servo motor 43, can be attained, however, only when the position of the test table or chamber is effectively at an angle which produces the desired resultant vector angle. This angle varies with operating conditions of the centrifuge. For that reason, there is provided a control 51 which can be set for any desired effective specimen table or chamber angle and constitutes au input to a synchromechanism 52 connected through a gearing 53 with the shaft 35. From the synchro 52 there is an output path 54 extending through the switch 11, when in the solid line position of FIGURE 1, and through the path 13 to the resolver 7.

When the input control 51 has been set at the desired table or chamber effective or apparent direction and the centrifuge is put into operation, then if the cosine of the radial vector as based upon the response of the radial accelerometer 31 and the sine of the tangential vector as based upon the response of the tangential accelerometer 32 are algebraically zero, the servo motor 43 is inactive. However, if the output of the amplifier 41 is other than zero, the servo motor 43 is effective upon the synchro 52 to produce an output through the resolver train, as

t previously described to rotate the table or chamber 6 until the angular position of that table or chamber is appropriate to afford the desired resultant direction of force upon the person or specimen.

With the operation of this structure, a specimen or individual on the test table or in the chamber is varied in rotational position about the test table or chamber axis as the acceleration or jerk of the centrifuge arm is varied and as the rotational velocity has different values, so that the direction of the resultant force upon the specimen or individual is substantially at the value or values selected.

In the arrangement particularly illustrated in FIGURE 2, a similar end is accomplished and in addition there is provided electronic circuitry effective to control the clutching mechanism as described in the copending application, above identified. As before, the centrifuge arm 2 is provided at an appropriate location with an accelerometer 101 effective in response to tangential forces accompanying acceleration and jerk. Similarly, the arm 2 is provided with an accelerometer 102 responsive to acceleration and jerk in a radial direction. Considering first the output of the tangential accelerometer, the re-` sponse thereof is impressed on a path 103 extending to a function multiplier 104 having the function of squaring. This is because it is desired to add the tangential and radial force vectors in a Pythagorean manner. Thus the output of the radial accelerometer 102 is sent on a path 106 to the function multiplier 104 in which it likewise is squared. The function multiplier 104 is provided with appropriate amplifiers 107 and 108 for the two values impressed upon it.

The square of the tangential force vector is carried on a path 109 into a summing device 111 and the square of the radial force vector is carried on a path 112 into the summing device 111. The radial force vector squared and the tangential force vector squared are added in the summing device 111. The sum is transmitted on a path 113 to a function multiplier 114 having the task of extracting the square root of that sum. The function multiplier 114 has appropriate amplifiers 116 and 117 respectively. The square root of the sum of the squares, i.e. a value representing the resultant force vector, is released from the function multiplier 114 on a path 118 which` extends to a function multiplier 119 effective to perform a division operation. Y

The output of the radial accelerometer 102 travelling in the path 106 is not only impressed upon the function multiplier 104, but likewise travels in a path 121 to the division device 119. This has an appropriate amplifier` 122 and iseffective to divide its two inputs (from 118 and 121) in order to furnish a value in its output path 123 equivalent to a sine function of the angle of the resultant corresponding to the acceleration inputs of the accelerometers 101 and 102. The output of the division device 119 travels in a path 123 to an algebraic summation device 124 the output of which travelling in a path 126 goes through an amplifier 127 and emerges on a path 128.

For various reasons, including those of force multiplication, standby duplication of facilities and others, the path 128 separates into four branches 131, 132, 133 and 134. These branches are identical and have identical functions so that they are described with similar reference numerals. The signal travelling in the paths 128 and 133, for example, is impressed upon a summing device 136 the output of which proceeds in a path 137 through an amplifier 138 and a path 139 to a servo valve 141. A mechanism 142 connects the servo valve to position an air valve 143 or the like functionally connected in a path 144 to a junction path 146 joining the outputs of all of the various branches 131, 132, 133 and 134 to be effective in unison (or in any group arrangement) upon a positioner 147. This is preferably a ram or motor for angularly positioning the carriage or specimen table on the centrifuge arm.

The relative location of the specimen table or carriage as arranged by the positioner 147 in response to the signalin the path 146 is impressed on a path 148 controlling a synchrotransmitter 149 having a gear train or other multiplier therein so that the relatively minor value introduced into the transmitter 149 is augmented for transmission over an extended output path 151. The multiplied value then passes to a receiver 152 preferably a synchroreceiver and gear train to reduce the transmitted value to the actual position angle or a small multiple thereof. From the receiver there is a short path 153 to position a mechanism 154 refiecting the relative carriage or test table angularity or position.

The output of the mechanism 154 travels in a path 156 to the summing device 124. Therein the desired position as refiected at the input path 123 is tested against the actual carriage or table position as reflected at the input path 156. If there is no error or discrepancy or difference in the two values then there is no further transmission through the sum output path 126 and the parts remain quiet. However, if the feedback impulse through the path 156 and the input pulse in the path 123 show an error, then the error is effective through the output path 126, as described, to operate the various motion devices to position the carriage or table until there is no longer any error.

Particularly for use with the type of structure shown in the mentioned copending application and to be responsive to the jerk of the specimen or carriage (the jerk being the first derivative of the acceleration) the tangential accelerometer 101 also has an output path 201 extending to a function multiplier 202 for performing the function of squaring. Similarly, the radial accelerometer 102 has an output path 203 extending to the function multiplier 202. The radial and tangential jerk values are appropriately squared as part of a process of deriving a vector resultant by the Pythagorean handling of a radial vector input and a tangential vector input.

The function multiplier 202 is provided with appropriate amplifiers 204 and 206 and affords an output in a path 207 for the square of the tangential input value and an output path 208 for the square of the radial input value. These two squares are both impressed upon a summing device 209. The sum is transmitted on a path 211 to a function multiplier 212 set to perform the function of extracting the square root. The function multiplier 212 has its own amplifiers 213 and 214. The root of the sum of the squares of the radial and tangential jerk components is transmitted on a path 216 to a summing device 217.

Also fed into the summing device 217 on a path 215 is a program signal from a function generator 220 set to provide an output correspondingy to the desired standard of onset or jerk. The signal can be observed at an oscilloscope 225 connected by a conductor L230 to the path 215. In the summing device 217 the actual input from the path 216 is compared with the desired program put in through the path 215 and the error, if any, forms the summing device output. The output from the summing device 217 is in two parallel paths 218 and 219.

From the path 218 the sum value travels into another summing device 221 the output of which travels through an amplifier 222 to a motor such as a hydraulically controlled air valve 223. This valve is effective to controlV the brake structure 224 for decelerating the rotation of the centrifuge arm. The effect of the operation of the brake mechanism 224 produces a corresponding feedback output in a path 226 extending to the summing device 221 so that this structure operates in accordance with usual feedback control. Similarly, the output in the path 219 from the summing device 217 is impressed upon another summing device 227 frorn which it travels through an amplifier 228 into a valve 229 such as a hydraulically controlled air valve for governing the clutch 231 coupling the flywheel to the centrifuge drive shaft, as described in the identified copending application. The effect of the clutch 231 is fed back through a path 232 into the summing device 227 so that the clutch function is made to follow the input impulse.

The effect of the brake 224 is transmitted not only through the feedback path 226, but also through a path 233 into a summing device 234 while the effect of the clutch 231 not only travels through the feedback path 232, but also goes through a path 235 into the summing device 234. The combination of the two values so introduced produces an output from the summing device 234 to govern the arm inertial load 236. The response of the centrifuge arm as represented by the load 236 is impressed upon a path 237 leading back to the tangential accelerometer 101 and the radial accelerometer 102. There is thus a feedback from the centrifuge arm so that the desired values of acceleration and jerk can be effectuated and controlled.

What is claimed is:

1. A vector alignment device comprising a centrifuge arm rotatable about a vertical axis, a test chamber on said arm and rotatable about a parallel Vertical axis, means for rotating said chamber about said parallel vertical axis, and means for controlling the operation of said rotating means including a first accelerometer on said arm and responsive to radial forces and a second accelerometer on said arm and responsive to tangential forces.

2. A vector alignment device comprising a centrifuge arm rotatable about a vertical axis, a test chamber on said arm and rotatable about a parallel vertical axis, means for rotating said chamber about said parallel vertical axis, a first accelerometer on said arm and responsive to radial forces, a second accelerometer on said arm and responsive to tangential forces, means for establishing the vectorial resultant of the responses of said first and said second accelerometers, and means for rotating said chamber about said parallel vertical axis to a position in accordance with the direction of said resultant.

3. A vector alignment device comprising a centrifuge arm rotatable about a vertical axis, a test chamber on said arm and rotatable about a parallel vertical axis, a first accelerometer on said arm and responsive to radial forces, means for determining the cosine of the response of said first accelerometer to said radial forces, a second accelerometer on said arm and responsive to tangential forces, means for determining the sine of the response of said second accelerometer to said tangential forces, means for establishing a net value equal to the difference between said sine value and said cosine value, and means for rotating said test chamber about said parallel vertical axis to a position corresponding to said net value.

4. A vector alignment device comprising a centrifuge arm rotatable about a vertical axis, a test chamberron said arm and rotatable about a parallel vertical axis, a first accelerometer on said arm and responsive to radial forces, a second accelerometer on said arm and responsive to tangential forces, means responsive to said iirst and second accelerometers for establishing the vectorial resultant of the responses thereof, means responsive to the rotary position of said chamber about said parallel Vertical axis, means for comparing said vectorial resultant with the response of said responsive means, and means controlled by said comparing means tor rotating said chamber about said parallel vertical axis until the direction of said chamber corresponds to the direction of said resultant.

5. A vector alignment device comprising a centrifuge having a rotor rotatable about a first axis, a test chamber on said rotor rotatable With respect thereto about a second axis parallel to said first axis, rst means on said rotor responsive to radial force thereon, second means on said rotor responsive to tangential force thereon, means controlled by said first means and said second means for establishing a vector resultant of said radial force and said tangential torce, and means for rotating said test chamber about said second axis into a position having a direction corresponding to the direction of said resultant.

6. A vector alignment device comprising a centrifuge having a rotor rotatable about a first axis, a test chamber on said rotor rotatable with respect thereto about a. second axis parallel to said rst axis, iirst means on said rotor responsive to radial force thereon, second means on said rotor responsive to tangential force thereon, means for establishing the square root of the sum of the squares of thel response of said iirst means and the response of said second means to provide a resultant, means for rotating said test chamber about said second axis, and means for operating said rotating means to rotate said test chamber into a position corresponding to said resultant.

3,011,333 Roth et al Dec. 5, 1961 Brown Dec. 3, 1957` 

1. A VECTOR ALIGNMENT DEVICE COMPRISING A CENTRIFUGE ARM ROTATABLE ABOUT A VERTICAL AXIS, A TEST CHAMBER ON SAID ARM AND ROTATABLE ABOUT A PARALLEL VERTICAL AXIS, MEANS FOR ROTATING SAID CHAMBER ABOUT SAID PARALLEL VERTICAL AXIS, AND MEANS FOR CONTROLLING THE OPERATION OF SAID ROTATING MEANS INCLUDING A FIRST ACCELEROMETER ON SAID ARM AND RESPONSIVE TO RADIAL FORCES AND A SECOND ACCELEROMETER ON SAID ARM AND RESPONSIVE TO TANGENTIAL FORCES. 